1. Technical Field
The present invention relates to a erosion control device for stabilizing soils and remedying beach and land erosion, a number of which can be assembled into a matrix for laying on or just below the surface of the ground or beach.
2. Background Information
Beach erosion and shore building are natural processes caused by the impact over time of waves on the shore. Waves breaking on the beach carry sedimentary material, also called littoral drift, onshore as the waves ascend the beach, and offshore as the waves retreat back. Waves arrive at an angle to the shore and retreat generally perpendicularly to the shore, resulting in a long shore current. This carries the littoral drift in a series of zigzags along the shoreline. The amount of littoral drift is dependent upon the speed of the waves; faster wave action translates to a higher amount of littoral drift. Littoral drift is deposited when the current (i.e., speed of the waves) slows. Thus, waves “steal” from one part of the beach to “feed” another part of the beach. During high tides, waves deposit sediment on higher areas of the beach while current close to the shoreline wears away at lower-lying areas of the beach. In the unusual event of an earthquake, enormous waves can be created that displace large amounts of sedimentary material.
The coast has some natural defenses against erosion. Gently sloping shores dissipate the energy of breaking waves, which decreases their speed as well as the amount of littoral drift. Dunes are natural seawalls, especially when they are covered with vegetation, which binds the sand. Inlets and bays are less subject to severe wave action and turbulence.
However, beach erosion and shore building are frequently accelerated by human activities. Heavy use and over development in shore areas, for example, hastens the erosion process. Damaging activities include dredging for marinas, bulldozing dunes, and pedestrian and vehicular traffic. Bulldozing dunes removes an important coastal defense, since dunes are natural seawalls. Pedestrian and vehicular traffic destroys vegetation and weakens bluffs and banks making them more susceptible to erosion. Obviously, removing large quantities of sand and sediment from a shore area without replacing it accelerates erosion.
Billions of dollars are spent each year on beach re-nourishment projects all along the coasts of the United States. Sand is brought in and spread on existing beaches in an effort to re-nourish them. Wide, attractive beaches in tourist-drawing seaside communities bring in more tourist dollars. Also, wide beaches are said to protect adjacent developed coastal areas from hurricane damage. In some areas where erosion is causing building structures to be washed away, re-nourishment is preventing loss of real estate every year. Beach re-nourishment, or replenishment, projects are controversial, though, because they are said to disrupt natural rhythms and cause more harm in the long run. Imported sand or sand pumped in from off shore dredges usually erodes away from the replenished beach at a faster rate.
Many man-made defenses against erosion, such as breakwaters, jetties, groins, seawalls, sand trapping devices, grass planting, and sand fences, also exist. However, such defenses have disadvantages. For example, breakwaters prevent wave erosion, but not longshore drifts, and are expensive. Seawalls deflect wave energy, but are very expensive and often utilized as a last resort because inevitably the sea slowly destroys sea walls. In fact, poorly designed or improperly installed erosion devices can actually accelerate erosion.
In sum, erosion is generally unstoppable. Yet people still flock to the seashore to build homes, hotels, and other structures directly in the path of erosion. Coastal residents continue to pay a high price, as erosion incessantly damages and claims their property. Thus, there is a need for an inexpensive erosion control device that works.